/*
   * ATAPI support.
   */
  
  #include <linux/kernel.h>

  #include <linux/cdrom.h>

  #include <linux/delay.h>

  #include <linux/export.h>

  #include <linux/ide.h>

  #include <linux/scatterlist.h>

  #include <linux/gfp.h>

  #include <scsi/scsi.h>

  #define DRV_NAME "ide-atapi"
  #define PFX DRV_NAME ": "

  #ifdef DEBUG
  #define debug_log(fmt, args...) \
  	printk(KERN_INFO "ide: " fmt, ## args)
  #else
  #define debug_log(fmt, args...) do {} while (0)
  #endif

  #define ATAPI_MIN_CDB_BYTES	12

  static inline int dev_is_idecd(ide_drive_t *drive)
  {

  	return drive->media == ide_cdrom || drive->media == ide_optical;

  }

  /*
   * Check whether we can support a device,
   * based on the ATAPI IDENTIFY command results.
   */
  int ide_check_atapi_device(ide_drive_t *drive, const char *s)
  {
  	u16 *id = drive->id;
  	u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
  
  	*((u16 *)&gcw) = id[ATA_ID_CONFIG];
  
  	protocol    = (gcw[1] & 0xC0) >> 6;
  	device_type =  gcw[1] & 0x1F;
  	removable   = (gcw[0] & 0x80) >> 7;
  	drq_type    = (gcw[0] & 0x60) >> 5;
  	packet_size =  gcw[0] & 0x03;
  
  #ifdef CONFIG_PPC
  	/* kludge for Apple PowerBook internal zip */
  	if (drive->media == ide_floppy && device_type == 5 &&
  	    !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
  	    strstr((char *)&id[ATA_ID_PROD], "ZIP"))
  		device_type = 0;
  #endif
  
  	if (protocol != 2)
  		printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI
  ",
  			s, drive->name, protocol);
  	else if ((drive->media == ide_floppy && device_type != 0) ||
  		 (drive->media == ide_tape && device_type != 1))
  		printk(KERN_ERR "%s: %s: invalid device type (0x%02x)
  ",
  			s, drive->name, device_type);
  	else if (removable == 0)
  		printk(KERN_ERR "%s: %s: the removable flag is not set
  ",
  			s, drive->name);
  	else if (drive->media == ide_floppy && drq_type == 3)
  		printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
  			"supported
  ", s, drive->name, drq_type);
  	else if (packet_size != 0)
  		printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
  			"bytes
  ", s, drive->name, packet_size);
  	else
  		return 1;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ide_check_atapi_device);

  void ide_init_pc(struct ide_atapi_pc *pc)
  {
  	memset(pc, 0, sizeof(*pc));

  }
  EXPORT_SYMBOL_GPL(ide_init_pc);

  /*

   * Add a special packet command request to the tail of the request queue,
   * and wait for it to be serviced.
   */
  int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,

  		      struct ide_atapi_pc *pc, void *buf, unsigned int bufflen)

  {
  	struct request *rq;
  	int error;
  
  	rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
  	rq->cmd_type = REQ_TYPE_SPECIAL;

  	rq->special = (char *)pc;

  	if (buf && bufflen) {
  		error = blk_rq_map_kern(drive->queue, rq, buf, bufflen,

  					GFP_NOIO);
  		if (error)
  			goto put_req;

  	}

  	memcpy(rq->cmd, pc->c, 12);
  	if (drive->media == ide_tape)
  		rq->cmd[13] = REQ_IDETAPE_PC1;
  	error = blk_execute_rq(drive->queue, disk, rq, 0);

  put_req:

  	blk_put_request(rq);

  	return error;
  }
  EXPORT_SYMBOL_GPL(ide_queue_pc_tail);

  int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
  {
  	struct ide_atapi_pc pc;
  
  	ide_init_pc(&pc);
  	pc.c[0] = TEST_UNIT_READY;

  	return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);

  }
  EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);

  int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
  {
  	struct ide_atapi_pc pc;
  
  	ide_init_pc(&pc);
  	pc.c[0] = START_STOP;
  	pc.c[4] = start;
  
  	if (drive->media == ide_tape)
  		pc.flags |= PC_FLAG_WAIT_FOR_DSC;

  	return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);

  }
  EXPORT_SYMBOL_GPL(ide_do_start_stop);

  int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
  {
  	struct ide_atapi_pc pc;

  	if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)

  		return 0;
  
  	ide_init_pc(&pc);
  	pc.c[0] = ALLOW_MEDIUM_REMOVAL;
  	pc.c[4] = on;

  	return ide_queue_pc_tail(drive, disk, &pc, NULL, 0);

  }
  EXPORT_SYMBOL_GPL(ide_set_media_lock);

  void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
  {
  	ide_init_pc(pc);
  	pc->c[0] = REQUEST_SENSE;
  	if (drive->media == ide_floppy) {
  		pc->c[4] = 255;
  		pc->req_xfer = 18;
  	} else {
  		pc->c[4] = 20;
  		pc->req_xfer = 20;
  	}
  }
  EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);

  void ide_prep_sense(ide_drive_t *drive, struct request *rq)
  {
  	struct request_sense *sense = &drive->sense_data;
  	struct request *sense_rq = &drive->sense_rq;
  	unsigned int cmd_len, sense_len;

  	int err;

  	switch (drive->media) {
  	case ide_floppy:
  		cmd_len = 255;
  		sense_len = 18;
  		break;
  	case ide_tape:
  		cmd_len = 20;
  		sense_len = 20;
  		break;
  	default:
  		cmd_len = 18;
  		sense_len = 18;
  	}
  
  	BUG_ON(sense_len > sizeof(*sense));

  	if (rq->cmd_type == REQ_TYPE_SENSE || drive->sense_rq_armed)

  		return;
  
  	memset(sense, 0, sizeof(*sense));
  
  	blk_rq_init(rq->q, sense_rq);

  	err = blk_rq_map_kern(drive->queue, sense_rq, sense, sense_len,
  			      GFP_NOIO);
  	if (unlikely(err)) {
  		if (printk_ratelimit())

  			printk(KERN_WARNING PFX "%s: failed to map sense "
  					    "buffer
  ", drive->name);

  		return;
  	}
  
  	sense_rq->rq_disk = rq->rq_disk;

  	sense_rq->cmd[0] = GPCMD_REQUEST_SENSE;
  	sense_rq->cmd[4] = cmd_len;

  	sense_rq->cmd_type = REQ_TYPE_SENSE;
  	sense_rq->cmd_flags |= REQ_PREEMPT;
  
  	if (drive->media == ide_tape)
  		sense_rq->cmd[13] = REQ_IDETAPE_PC1;
  
  	drive->sense_rq_armed = true;
  }
  EXPORT_SYMBOL_GPL(ide_prep_sense);

  int ide_queue_sense_rq(ide_drive_t *drive, void *special)

  {

  	/* deferred failure from ide_prep_sense() */
  	if (!drive->sense_rq_armed) {

  		printk(KERN_WARNING PFX "%s: error queuing a sense request
  ",

  		       drive->name);
  		return -ENOMEM;
  	}

  
  	drive->sense_rq.special = special;
  	drive->sense_rq_armed = false;
  
  	drive->hwif->rq = NULL;

  	elv_add_request(drive->queue, &drive->sense_rq, ELEVATOR_INSERT_FRONT);

  	return 0;

  }
  EXPORT_SYMBOL_GPL(ide_queue_sense_rq);

  /*
   * Called when an error was detected during the last packet command.

   * We queue a request sense packet command at the head of the request
   * queue.

   */

  void ide_retry_pc(ide_drive_t *drive)

  {

  	struct request *failed_rq = drive->hwif->rq;

  	struct request *sense_rq = &drive->sense_rq;

  	struct ide_atapi_pc *pc = &drive->request_sense_pc;
  
  	(void)ide_read_error(drive);

  
  	/* init pc from sense_rq */
  	ide_init_pc(pc);
  	memcpy(pc->c, sense_rq->cmd, 12);

  	if (drive->media == ide_tape)

  		drive->atapi_flags |= IDE_AFLAG_IGNORE_DSC;

  	/*
  	 * Push back the failed request and put request sense on top
  	 * of it.  The failed command will be retried after sense data
  	 * is acquired.
  	 */

  	drive->hwif->rq = NULL;

  	ide_requeue_and_plug(drive, failed_rq);

  	if (ide_queue_sense_rq(drive, pc)) {

  		blk_start_request(failed_rq);

  		ide_complete_rq(drive, -EIO, blk_rq_bytes(failed_rq));
  	}

  }
  EXPORT_SYMBOL_GPL(ide_retry_pc);

  int ide_cd_expiry(ide_drive_t *drive)
  {

  	struct request *rq = drive->hwif->rq;

  	unsigned long wait = 0;
  
  	debug_log("%s: rq->cmd[0]: 0x%x
  ", __func__, rq->cmd[0]);
  
  	/*
  	 * Some commands are *slow* and normally take a long time to complete.
  	 * Usually we can use the ATAPI "disconnect" to bypass this, but not all
  	 * commands/drives support that. Let ide_timer_expiry keep polling us
  	 * for these.
  	 */
  	switch (rq->cmd[0]) {
  	case GPCMD_BLANK:
  	case GPCMD_FORMAT_UNIT:
  	case GPCMD_RESERVE_RZONE_TRACK:
  	case GPCMD_CLOSE_TRACK:
  	case GPCMD_FLUSH_CACHE:
  		wait = ATAPI_WAIT_PC;
  		break;
  	default:
  		if (!(rq->cmd_flags & REQ_QUIET))

  			printk(KERN_INFO PFX "cmd 0x%x timed out
  ",

  					 rq->cmd[0]);
  		wait = 0;
  		break;
  	}
  	return wait;
  }
  EXPORT_SYMBOL_GPL(ide_cd_expiry);

  int ide_cd_get_xferlen(struct request *rq)
  {

  	switch (rq->cmd_type) {

  	case REQ_TYPE_FS:

  		return 32768;

  	case REQ_TYPE_SENSE:
  	case REQ_TYPE_BLOCK_PC:
  	case REQ_TYPE_ATA_PC:

  		return blk_rq_bytes(rq);

  	default:

  		return 0;

  	}

  }
  EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);

  void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
  {

  	struct ide_taskfile tf;

  	drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
  				     IDE_VALID_LBAM | IDE_VALID_LBAH);

  	*bcount = (tf.lbah << 8) | tf.lbam;
  	*ireason = tf.nsect & 3;

  }
  EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);

  /*

   * Check the contents of the interrupt reason register and attempt to recover if
   * there are problems.
   *
   * Returns:
   * - 0 if everything's ok
   * - 1 if the request has to be terminated.
   */
  int ide_check_ireason(ide_drive_t *drive, struct request *rq, int len,
  		      int ireason, int rw)
  {
  	ide_hwif_t *hwif = drive->hwif;
  
  	debug_log("ireason: 0x%x, rw: 0x%x
  ", ireason, rw);
  
  	if (ireason == (!rw << 1))
  		return 0;
  	else if (ireason == (rw << 1)) {
  		printk(KERN_ERR PFX "%s: %s: wrong transfer direction!
  ",
  				drive->name, __func__);
  
  		if (dev_is_idecd(drive))
  			ide_pad_transfer(drive, rw, len);
  	} else if (!rw && ireason == ATAPI_COD) {
  		if (dev_is_idecd(drive)) {
  			/*
  			 * Some drives (ASUS) seem to tell us that status info
  			 * is available.  Just get it and ignore.
  			 */
  			(void)hwif->tp_ops->read_status(hwif);
  			return 0;
  		}
  	} else {
  		if (ireason & ATAPI_COD)
  			printk(KERN_ERR PFX "%s: CoD != 0 in %s
  ", drive->name,
  					__func__);
  
  		/* drive wants a command packet, or invalid ireason... */
  		printk(KERN_ERR PFX "%s: %s: bad interrupt reason 0x%02x
  ",
  				drive->name, __func__, ireason);
  	}
  
  	if (dev_is_idecd(drive) && rq->cmd_type == REQ_TYPE_ATA_PC)
  		rq->cmd_flags |= REQ_FAILED;
  
  	return 1;
  }
  EXPORT_SYMBOL_GPL(ide_check_ireason);
  
  /*

   * This is the usual interrupt handler which will be called during a packet
   * command.  We will transfer some of the data (as requested by the drive)
   * and will re-point interrupt handler to us.
   */
  static ide_startstop_t ide_pc_intr(ide_drive_t *drive)

  {

  	struct ide_atapi_pc *pc = drive->pc;

  	ide_hwif_t *hwif = drive->hwif;

  	struct ide_cmd *cmd = &hwif->cmd;

  	struct request *rq = hwif->rq;

  	const struct ide_tp_ops *tp_ops = hwif->tp_ops;

  	unsigned int timeout, done;

  	u16 bcount;

  	u8 stat, ireason, dsc = 0;

  	u8 write = !!(pc->flags & PC_FLAG_WRITING);

  
  	debug_log("Enter %s - interrupt handler
  ", __func__);

  	timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
  					       : WAIT_TAPE_CMD;

  	/* Clear the interrupt */

  	stat = tp_ops->read_status(hwif);

  
  	if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {

  		int rc;

  		drive->waiting_for_dma = 0;
  		rc = hwif->dma_ops->dma_end(drive);

  		ide_dma_unmap_sg(drive, cmd);

  
  		if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {

  			if (drive->media == ide_floppy)

  				printk(KERN_ERR PFX "%s: DMA %s error
  ",

  					drive->name, rq_data_dir(pc->rq)
  						     ? "write" : "read");
  			pc->flags |= PC_FLAG_DMA_ERROR;

  		} else

  			rq->resid_len = 0;

  		debug_log("%s: DMA finished
  ", drive->name);
  	}
  
  	/* No more interrupts */

  	if ((stat & ATA_DRQ) == 0) {

  		int uptodate, error;

  		debug_log("Packet command completed, %d bytes transferred
  ",

  			  blk_rq_bytes(rq));

  
  		pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
  
  		local_irq_enable_in_hardirq();

  		if (drive->media == ide_tape &&

  		    (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
  			stat &= ~ATA_ERR;

  		if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {

  			/* Error detected */
  			debug_log("%s: I/O error
  ", drive->name);

  			if (drive->media != ide_tape)

  				pc->rq->errors++;

  			if (rq->cmd[0] == REQUEST_SENSE) {

  				printk(KERN_ERR PFX "%s: I/O error in request "
  						"sense command
  ", drive->name);

  				return ide_do_reset(drive);
  			}

  			debug_log("[cmd %x]: check condition
  ", rq->cmd[0]);

  
  			/* Retry operation */

  			ide_retry_pc(drive);

  			/* queued, but not started */
  			return ide_stopped;
  		}

  		pc->error = 0;

  
  		if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
  			dsc = 1;

  		/*
  		 * ->pc_callback() might change rq->data_len for
  		 * residual count, cache total length.
  		 */

  		done = blk_rq_bytes(rq);

  		/* Command finished - Call the callback function */

  		uptodate = drive->pc_callback(drive, dsc);
  
  		if (uptodate == 0)
  			drive->failed_pc = NULL;

  		if (rq->cmd_type == REQ_TYPE_SPECIAL) {

  			rq->errors = 0;

  			error = 0;

  		} else {

  			if (rq->cmd_type != REQ_TYPE_FS && uptodate <= 0) {

  				if (rq->errors == 0)
  					rq->errors = -EIO;
  			}

  			error = uptodate ? 0 : -EIO;

  		}

  		ide_complete_rq(drive, error, blk_rq_bytes(rq));

  		return ide_stopped;
  	}
  
  	if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
  		pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;

  		printk(KERN_ERR PFX "%s: The device wants to issue more "
  				"interrupts in DMA mode
  ", drive->name);

  		ide_dma_off(drive);
  		return ide_do_reset(drive);
  	}

  	/* Get the number of bytes to transfer on this interrupt. */
  	ide_read_bcount_and_ireason(drive, &bcount, &ireason);

  	if (ide_check_ireason(drive, rq, bcount, ireason, write))

  		return ide_do_reset(drive);

  	done = min_t(unsigned int, bcount, cmd->nleft);
  	ide_pio_bytes(drive, cmd, write, done);

  	/* Update transferred byte count */

  	rq->resid_len -= done;

  
  	bcount -= done;
  
  	if (bcount)
  		ide_pad_transfer(drive, write, bcount);

  	debug_log("[cmd %x] transferred %d bytes, padded %d bytes, resid: %u
  ",
  		  rq->cmd[0], done, bcount, rq->resid_len);

  	/* And set the interrupt handler again */

  	ide_set_handler(drive, ide_pc_intr, timeout);

  	return ide_started;
  }

  static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,

  				u16 bcount, u8 dma)

  {

  	cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
  	cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
  			    IDE_VALID_FEATURE | valid_tf;

  	cmd->tf.command = ATA_CMD_PACKET;

  	cmd->tf.feature = dma;		/* Use PIO/DMA */
  	cmd->tf.lbam    = bcount & 0xff;
  	cmd->tf.lbah    = (bcount >> 8) & 0xff;

  }

  static u8 ide_read_ireason(ide_drive_t *drive)
  {

  	struct ide_taskfile tf;

  	drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);

  	return tf.nsect & 3;

  }

  static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
  {

  	int retries = 100;

  	while (retries-- && ((ireason & ATAPI_COD) == 0 ||
  		(ireason & ATAPI_IO))) {

  		printk(KERN_ERR PFX "%s: (IO,CoD != (0,1) while issuing "

  				"a packet command, retrying
  ", drive->name);
  		udelay(100);

  		ireason = ide_read_ireason(drive);

  		if (retries == 0) {

  			printk(KERN_ERR PFX "%s: (IO,CoD != (0,1) while issuing"
  					" a packet command, ignoring
  ",

  					drive->name);

  			ireason |= ATAPI_COD;
  			ireason &= ~ATAPI_IO;

  		}
  	}
  
  	return ireason;
  }

  static int ide_delayed_transfer_pc(ide_drive_t *drive)
  {
  	/* Send the actual packet */
  	drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
  
  	/* Timeout for the packet command */
  	return WAIT_FLOPPY_CMD;
  }
  
  static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)

  {

  	struct ide_atapi_pc *uninitialized_var(pc);

  	ide_hwif_t *hwif = drive->hwif;

  	struct request *rq = hwif->rq;

  	ide_expiry_t *expiry;
  	unsigned int timeout;

  	int cmd_len;

  	ide_startstop_t startstop;
  	u8 ireason;

  	if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {

  		printk(KERN_ERR PFX "%s: Strange, packet command initiated yet "

  				"DRQ isn't asserted
  ", drive->name);
  		return startstop;
  	}

  	if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
  		if (drive->dma)
  			drive->waiting_for_dma = 1;
  	}

  	if (dev_is_idecd(drive)) {
  		/* ATAPI commands get padded out to 12 bytes minimum */
  		cmd_len = COMMAND_SIZE(rq->cmd[0]);
  		if (cmd_len < ATAPI_MIN_CDB_BYTES)
  			cmd_len = ATAPI_MIN_CDB_BYTES;

  		timeout = rq->timeout;
  		expiry  = ide_cd_expiry;

  	} else {

  		pc = drive->pc;

  		cmd_len = ATAPI_MIN_CDB_BYTES;
  
  		/*
  		 * If necessary schedule the packet transfer to occur 'timeout'

  		 * milliseconds later in ide_delayed_transfer_pc() after the

  		 * device says it's ready for a packet.
  		 */
  		if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
  			timeout = drive->pc_delay;
  			expiry = &ide_delayed_transfer_pc;
  		} else {
  			timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
  							       : WAIT_TAPE_CMD;
  			expiry = NULL;
  		}

  
  		ireason = ide_read_ireason(drive);
  		if (drive->media == ide_tape)
  			ireason = ide_wait_ireason(drive, ireason);
  
  		if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {

  			printk(KERN_ERR PFX "%s: (IO,CoD) != (0,1) while "
  				"issuing a packet command
  ", drive->name);

  
  			return ide_do_reset(drive);
  		}

  	}

  	hwif->expiry = expiry;

  	/* Set the interrupt routine */

  	ide_set_handler(drive,
  			(dev_is_idecd(drive) ? drive->irq_handler
  					     : ide_pc_intr),

  			timeout);

  	/* Send the actual packet */
  	if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
  		hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);

  	/* Begin DMA, if necessary */

  	if (dev_is_idecd(drive)) {
  		if (drive->dma)
  			hwif->dma_ops->dma_start(drive);
  	} else {
  		if (pc->flags & PC_FLAG_DMA_OK) {
  			pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
  			hwif->dma_ops->dma_start(drive);
  		}

  	}

  	return ide_started;
  }

  ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)

  {

  	struct ide_atapi_pc *pc;

  	ide_hwif_t *hwif = drive->hwif;

  	ide_expiry_t *expiry = NULL;

  	struct request *rq = hwif->rq;

  	unsigned int timeout, bytes;

  	u16 bcount;

  	u8 valid_tf;

  	u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);

  	if (dev_is_idecd(drive)) {

  		valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;

  		bcount = ide_cd_get_xferlen(rq);

  		expiry = ide_cd_expiry;

  		timeout = ATAPI_WAIT_PC;

  		if (drive->dma)
  			drive->dma = !ide_dma_prepare(drive, cmd);

  	} else {

  		pc = drive->pc;

  		valid_tf = IDE_VALID_DEVICE;

  		bytes = blk_rq_bytes(rq);

  		bcount = ((drive->media == ide_tape) ? bytes
  						     : min_t(unsigned int,
  							     bytes, 63 * 1024));

  		/* We haven't transferred any data yet */
  		rq->resid_len = bcount;

  		if (pc->flags & PC_FLAG_DMA_ERROR) {
  			pc->flags &= ~PC_FLAG_DMA_ERROR;
  			ide_dma_off(drive);
  		}

  		if (pc->flags & PC_FLAG_DMA_OK)
  			drive->dma = !ide_dma_prepare(drive, cmd);

  		if (!drive->dma)
  			pc->flags &= ~PC_FLAG_DMA_OK;

  
  		timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
  						       : WAIT_TAPE_CMD;

  	}

  	ide_init_packet_cmd(cmd, valid_tf, bcount, drive->dma);

  
  	(void)do_rw_taskfile(drive, cmd);

  	if (drq_int) {

  		if (drive->dma)
  			drive->waiting_for_dma = 0;

  		hwif->expiry = expiry;

  	}

  
  	ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
  
  	return drq_int ? ide_started : ide_transfer_pc(drive);

  }
  EXPORT_SYMBOL_GPL(ide_issue_pc);